There are a number of instances where this kind of tax system becomes absolutely regressive: 1) You will force people out of their homes after a certain point.

There are a number of instances where this kind of tax system becomes absolutely regressive: 1) You will force people out of their homes after a certain point. By delaying the payment on the taxes until sale, after some number of decades the amount of tax owed upon sale will be far larger than the value of the property, and no buyers will be found. So you're going to squeeze out not only ordinary family-residential ownership (nobody wants to buy a house that they know they'll just need to resell in 40 years or else pass some point of no return) but also commercial development (even if you can afford to buy multiple tax-deferred properties, you'd be developing on the land knowing that it'll be almost impossible to sell it on towards future development in a few decades) and infrastructure development (what, the government is going to pay itself on its enormous property tax bill when it needs to eminent domain private property to build new infrastructure?). 2) What happens if the old person never sells? Their children inherit the huge property. Do they owe the deferred tax upon transference? Does the tax continue to defer? If the tax is owed upon transference, and the children are unable to pay, and they're unable to find a buyer because the market crashed and no buyer is willing to pay that much tax - what happens? Does the government bail the children out of its own tax bill? Not only does deferring the taxes get rid of the primary benefit of the property taxes for local governments (stable and dependable tax income year over year), but it dramatically incentivizes rentals and short-term ownership. Short-term ownership is terrible because it disincentivizes investment in the property itself. Ultimately development disappears and you have people either long-term renting from short-term owners shuffling the properties among themselves or short-term owning, and since the people who do need short-term housing are people like college interns, you'll find that the amount of talent is only going to decrease and put further upper wage pressure on engineering salaries.